Seismic isolation device
The laminated structure with specific material ratios and properties in seismic isolation devices addresses the challenge of high surface pressure, enhancing stability and seismic isolation by preventing buckling and supporting increased axial forces.
Patent Information
- Application Number
- JP2022095166
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-06-13
- Publication Date
- 2026-02-24
- Estimated Expiration
- 2042-06-13
AI Technical Summary
Conventional seismic isolation devices face limitations in terms of increasing surface pressure, which affects their ability to withstand high loads and maintain stability during earthquakes.
A laminated structure comprising alternately stacked hard and soft material layers, with specific ratios and properties that satisfy formulas (1) and (4), allowing for high surface pressure and preventing buckling before fracture, thereby enhancing stability and seismic isolation performance.
The device can withstand high surface pressures without buckling, supporting increased axial forces and providing improved seismic isolation by prolonging the structure's period, ensuring stability and reducing the risk of buckling during earthquakes.
Smart Images
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Abstract
Description
[Technical Field]
[0001] The present invention relates to a seismic isolation device. [Background technology]
[0002] BACKGROUND ART Conventional seismic isolation devices include those equipped with a laminated structure having hard material layers and soft material layers alternately stacked in the vertical direction (for example, Patent Document 1). [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Patent No. 6482974 specification Summary of the Invention [Problem to be solved by the invention]
[0004] However, conventional seismic isolation devices have room for improvement in terms of increasing surface pressure.
[0005] An object of the present invention is to provide a seismic isolation device that can be subjected to high surface pressure. [Means for solving the problem]
[0006] The seismic isolation device of the present invention comprises: A seismic isolation device comprising a laminated structure having hard material layers and soft material layers alternately stacked in a vertical direction, The following formula (1) is satisfied.
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[0007] In the seismic isolation device of the present invention, It is preferable that the soft material layer has a shear modulus of elasticity of 0.35 MPa or more. In this case, it is easy to obtain a seismic isolation device that satisfies formula (1).
[0008] In the seismic isolation device of the present invention, It is preferable that the total thickness of all the soft material layers is 160 mm or more. In this case, it is possible to increase the period and also ensure a large limit deformation. [Effects of the Invention]
[0009] According to the present invention, it is possible to provide a seismic isolation device that can withstand high surface pressure. [Brief explanation of the drawings]
[0010] [Figure 1] 1 is an axial cross-sectional view schematically showing a seismic isolation device according to one embodiment of the present invention. [Figure 2] FIG. 1 is a perspective view schematically showing a seismic isolation device model used in the analysis. [Figure 3] 10A and 10B are diagrams showing analysis results of comparative examples and examples of the seismic isolation device of the present invention. [Figure 4] 10A and 10B are diagrams showing analysis results of comparative examples and examples of the seismic isolation device of the present invention. [Figure 5] 10A and 10B are diagrams showing analysis results of comparative examples and examples of the seismic isolation device of the present invention. [Figure 6] 10A and 10B are diagrams showing analysis results of comparative examples and examples of the seismic isolation device of the present invention. [Figure 7]10A and 10B are diagrams showing analysis results of comparative examples and examples of the seismic isolation device of the present invention. [Figure 8] 10A and 10B are diagrams showing analysis results of comparative examples and examples of the seismic isolation device of the present invention. DETAILED DESCRIPTION OF THE INVENTION
[0011] The seismic isolation device of the present invention is suitable for being placed between the superstructure and substructure of a structure (for example, buildings such as buildings, condominiums, detached houses, warehouses, and bridges) in order to suppress the transmission of earthquake vibrations to the structure. The seismic isolation device of the present invention is suitable for being provided on pillars so as to support the pillars of the structure, and for example, it is suitable for one device to be provided on each pillar. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a seismic isolation device according to the present invention will be described with reference to the drawings. Common components in the various drawings are designated by the same reference numerals.
[0012] Fig. 1 is a diagram for explaining a seismic isolation device 1 according to one embodiment of the present invention. Fig. 1 is an axial cross-sectional view that schematically shows the seismic isolation device 1 according to this embodiment in a state where no horizontal deformation occurs. As shown in FIG. 1, the seismic isolation device 1 of this embodiment includes a laminated structure 3, a pair of upper and lower connecting steel plates 7, and a pair of upper and lower flanges 8.
[0013] In this specification, the "central axis O" of the seismic isolation device 1 (hereinafter simply referred to as the "central axis O") is the central axis of the laminated structure 3. The central axis O of the seismic isolation device 1 is oriented to extend in the vertical direction. In this specification, the "axial direction" of the seismic isolation device 1 is a direction parallel to the central axis O of the seismic isolation device 1. The "axial inner side" of the seismic isolation device 1 refers to the side closer to the axial center of the laminated structure 3 in the axial direction, and the "axial outer side" of the seismic isolation device 1 refers to the side farther from the axial center of the laminated structure 3 in the axial direction. Furthermore, the "direction perpendicular to the axis" of the seismic isolation device 1 is a direction perpendicular to the axial direction of the seismic isolation device 1. Furthermore, the "inner peripheral side," "outer peripheral side," "radial direction," and "circumferential direction" of the seismic isolation device 1 refer to the "inner peripheral side," "outer peripheral side," "radial direction," and "circumferential direction," respectively, when the central axis O of the seismic isolation device 1 is the center. Additionally, "upper" and "lower" refer to "upper" and "lower" in the vertical direction, respectively.
[0014] The laminated structure 3 has a plurality of hard material layers 4, a plurality of soft material layers 5, and a covering layer 6. The hard material layers 4 and the soft material layers 5 are stacked alternately in the vertical direction. Each hard material layer 4 and each soft material layer 5 are arranged coaxially; that is, the central axis of each hard material layer 4 and each soft material layer 5 is positioned on the central axis O of the seismic isolation device 1. It is preferable that soft material layers 5 are arranged on both the upper and lower ends of the laminated structure 3.
[0015] The hard material layer 4 is made of a hard material. As the hard material constituting the hard material layer 4, metal is preferable, and steel is more preferable. The thickness of each hard material layer 4 is preferably the same as in the example of FIG. 1, but may be different from each other. The widths of the hard material layers 4 are preferably the same as each other, as in the example of FIG. 1, but may be different from each other.
[0016] The soft material layer 5 is made of a soft material that is softer than the hard material layer 4. An elastic body is preferable as the soft material that makes up the soft material layer 5, and rubber is more preferable. The rubber that can make up the soft material layer 5 is preferably natural rubber or synthetic rubber (such as high damping rubber). The thickness of each soft material layer 5 is preferably the same as in the example of FIG. 1, but may be different from each other. The width of each soft material layer 5 is preferably the same as that of each hard material layer 4, as in the example of Fig. 1. In this case, the width of each soft material layer 5 is preferably the same as that of each hard material layer 4, as in the example of Fig. 1. However, the widths of each soft material layer 5 may be different from each other.
[0017] The covering layer 6 covers the outer peripheral surfaces of the hard material layer 4 and the soft material layer 5. The material constituting the covering layer 6 is preferably an elastic body, more preferably rubber. The material constituting the covering layer 6 may be the same as the soft material constituting the soft material layer 5, or may be different from the soft material constituting the soft material layer 5. The covering layer 6 is formed integrally with the soft material layer 5 . 1, the coating layer 6 covers the entire outer peripheral surfaces of the hard material layer 4 and the soft material layer 5, and thus constitutes the entire outer peripheral surface of the laminated structure 3. However, the coating layer 6 may cover only a portion of the outer peripheral surfaces of the hard material layer 4 and the soft material layer 5, and thus may constitute only a portion of the outer peripheral surface of the laminated structure 3. Furthermore, the laminated structure 3 does not necessarily have to have the covering layer 6.
[0018] The hard material layer 4, the soft material layer 5, and the covering layer 6 (and thus the laminated structure 3) may each have any outer edge shape, such as a polygonal shape (such as a square), a circle, etc., in a cross section perpendicular to the axis. When the hard material layer 4, the soft material layer 5, and the covering layer 6 (and thus the laminated structure 3) each have a polygonal shape in a cross section perpendicular to the axis, each corner of the polygonal shape may be angular or may be curved by C-chamfering or the like.
[0019] The width of the laminated structure 3 is preferably constant along the axial direction as in the example of FIG. 1, but may vary along the axial direction.
[0020] In this specification, the "width" of a member such as the laminated structure 3, the hard material layer 4, the soft material layer 5, the connecting steel plates 7, the flanges 8, etc. refers to the distance between two intersections of a line passing through the center of gravity of the outer edge shape of the member in a cross section perpendicular to the axis and the outer edge shape, in a direction in which the distance between the two intersections is smallest. For example, if the outer edge of the member is circular in a cross section perpendicular to the axis, the "width" corresponds to the diameter of the circle, and if the outer edge of the member is square in a cross section perpendicular to the axis, the "width" corresponds to the length of one side of the square.
[0021] In the example of FIG. 1 , the laminated structure 3 has each hard material layer 4 and each soft material layer 5 configured as a solid, but is not limited to this. For example, the laminated structure 3 may have each hard material layer 4 and each soft material layer 5 configured as an annular, and the laminated structure 3 may have a central hole extending in the axial direction on its central axis O by the central holes of each hard material layer 4 and each soft material layer 5. In this case, a columnar body may be disposed in the central hole. The columnar body is preferably configured to be able to absorb vibration energy by plastic deformation. The columnar body may be made of, for example, lead, tin, a tin alloy, or a thermoplastic resin.
[0022] The laminated structure 3 is disposed between a pair of flanges 8 . Of the pair of flanges 8, the upper flange 8 is configured to be connected to the superstructure (the building itself, etc.; more specifically, the pillars of the building itself) of a structure (for example, a building, condominium, detached house, warehouse, or bridge) by fastening or the like when the superstructure is placed on top of the flange 8. Of the pair of flanges 8, the lower flange 8 is configured to be connected to the substructure (foundation, etc.) of the structure by fastening or the like. The flange 8 is preferably made of metal, more preferably steel. The flange 8 may have any outer edge shape, such as a polygonal shape (such as a square) or a circle, in a cross section perpendicular to the axis.
[0023] The pair of connecting steel plates 7 are disposed between the laminated structure 3 and the pair of flanges 8 . The pair of connecting steel plates 7 are respectively connected to the upper and lower surfaces of the laminated structure 3 by, for example, adhesion (vulcanization adhesion and / or adhesion with an adhesive, etc.) etc. The pair of connecting steel plates 7 are also connected to a pair of flanges 8 by fastening them with fastening members f. The connecting steel plates 7 are made of a hard material. As the hard material constituting the connecting steel plates 7, metal is preferable, and steel is more preferable.
[0024] However, the seismic isolation device 1 does not necessarily have to include the pair of connecting steel plates 7. In this case, it is preferable that the pair of flanges 8 are connected to the upper and lower surfaces of the laminated structure 3, respectively, by, for example, adhesion (vulcanization adhesion and / or adhesion with an adhesive, etc.).
[0025] The seismic isolation device 1 of this embodiment preferably has a long-term allowable surface pressure of 18 MPa or more and 25 MPa or less. Here, "long-term allowable surface pressure" corresponds to "Fc / 3" of "allowable stress against long-term forces" as defined in Article 6 of the "Ministry of Construction Notification No. 2009 of 2000."
[0026] Moreover, the seismic isolation device 1 of this embodiment satisfies the following formula (1).
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[0027] In the above formula (1), the left side (X(1-e Y)) represents the buckling strain, i.e., the shear strain of the seismic isolation device 1 when buckling occurs in the seismic isolation device 1 during horizontal deformation of the seismic isolation device 1. Generally, the buckling strain can be adjusted by the structure of the seismic isolation device. In the above formula (1), the right-hand side (4) represents the fracture strain, i.e., the shear strain of the seismic isolation device 1 when fracture occurs in the seismic isolation device 1 during horizontal deformation of the seismic isolation device 1. Generally, the fracture limit strain is defined as 400%. Therefore, the fracture strain corresponds to a shear strain of 400%. The number "4" on the right-hand side of the above formula (1) represents a shear strain of 400%. Generally, shear strain cannot be adjusted by the structure of the seismic isolation device. The above formula (1) is designed especially for seismic isolation devices with a long-term allowable surface pressure of 18 MPa or more and 25 MPa or less. The above formula (1) is an empirical formula newly discovered by the inventor of the present invention based on the results of FEM analysis of comparative examples and examples described later. Specifically, formula (1) is an empirical formula derived from FEM analysis in which S2 contributes linearly to buckling, and S1 and S3 contribute exponentially to buckling.
[0028] In order to obtain a seismic isolation device 1 that satisfies the above formula (1), it is sufficient to adjust the dimensions and number of the hard material layers 4 and soft material layers 5, the shear modulus of elasticity of the soft material layers 5, etc. The shape of the laminated structure 3 in the cross section perpendicular to the axis does not have much effect on whether the above formula (1) is satisfied.
[0029] The above formula (1) indicates that when a high surface pressure equivalent to a short-term allowable surface pressure σ, which is approximately twice the long-term allowable surface pressure of, for example, 18 MPa or more and 25 MPa or less, is applied to the seismic isolation device 1, fracture occurs before buckling during horizontal deformation of the seismic isolation device 1; in other words, buckling does not occur until the fracture strain (shear strain 400%) is reached. Generally, when a high surface pressure is applied to a seismic isolation device, the device is prone to buckling during horizontal deformation. Conventional seismic isolation devices do not satisfy the above formula (1), and when a high surface pressure equivalent to a short-term allowable surface pressure σ, which is approximately twice the long-term allowable surface pressure of 18 MPa to 25 MPa, is applied, there is a risk that the seismic isolation device will buckle before breaking during horizontal deformation. On the other hand, in the case of the seismic isolation device 1 of this embodiment that satisfies the above formula (1), when a high surface pressure equivalent to a short-term allowable surface pressure σ, which is approximately twice the long-term allowable surface pressure of, for example, 18 MPa to 25 MPa, is applied to the seismic isolation device, fracture occurs before buckling during horizontal deformation of the seismic isolation device 1, so that the occurrence of buckling can be suppressed over a longer shear strain region, thereby improving stability. Therefore, even if large horizontal deformation occurs under high surface pressure during an earthquake, the device can withstand it without buckling; in other words, high surface pressure is possible. Generally, when a seismic isolation device is installed on a column, the surface pressure of the seismic isolation device corresponds to the axial force of the column divided by the cross-sectional area of the soft material layer of the seismic isolation device. In recent years, the axial force of columns has been increasing, and there is a demand for seismic isolation devices that can support such high axial forces. Two possible methods for meeting this demand are to increase the surface pressure of the seismic isolation device or to increase the width of the laminated structure of the seismic isolation device. However, because there is a limit to the size of the machines (e.g., vulcanizers) used to manufacture seismic isolation devices, there is a practical limit to how much the width of the laminated structure of the seismic isolation device can be increased. On the other hand, according to this embodiment, the surface pressure of the seismic isolation device 1 can be increased, allowing the seismic isolation device 1 to support a higher axial force without having to be enlarged. Furthermore, according to this embodiment, the surface pressure of the seismic isolation device 1 can be increased, which enables the structure to have a longer period (in other words, the structure will sway more slowly), thereby improving the seismic isolation performance of the seismic isolation device 1. The period T of a structure is expressed by the following equation (3), and since m (mass) in equation (3) is proportional to the surface pressure, the period T can be lengthened by increasing the surface pressure of the seismic isolation device 1.
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[0030] In addition, from the viewpoint of high surface pressure, etc., assuming a case where the fracture strain exceeds 400%, it is preferable that the seismic isolation device 1 satisfies the following formula (4), and it is even more preferable that it satisfies the following formula (5).
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[0031] The long-term allowable surface pressure of the seismic isolation device 1 is preferably greater than 18 MPa, more preferably 20 MPa or more, and is preferably, for example, 20 MPa. The short-term allowable surface pressure σ of the seismic isolation device 1 is preferably 36 MPa or more, more preferably more than 36 MPa, and even more preferably 40 MPa or more. The short-term allowable surface pressure σ of the seismic isolation device 1 is preferably 50 MPa or less. For example, the short-term allowable surface pressure σ of the seismic isolation device 1 is preferably 40 MPa.
[0032] The shear modulus of elasticity of the soft material layer 5 is preferably 0.350 MPa or more. In this case, it is easy to obtain a seismic isolation device 1 that satisfies formula (1). This also makes the seismic isolation device 1 less susceptible to buckling. From the same viewpoint, the shear modulus of elasticity of the soft material layer 5 is more preferably 0.390 MPa or more, for example, 0.392 MPa or more, and particularly preferably 0.392 MPa. The shear modulus of elasticity of the soft material layer 5 is preferably, for example, 0.6 MPa or less. In this specification, the "shear modulus" of the soft material layer 5 refers to the static shear modulus measured in accordance with JIS K 6254:2016. The higher the shear modulus of elasticity of the soft material layer 5, the larger the buckling strain.
[0033] The width of the laminated structure 3 (and consequently the hard material layer 4 and the soft material layer 5) is preferably 1800 mm or less, which makes it easier to manufacture the seismic isolation device 1.
[0034] The total thickness of all the soft material layers 5 is preferably 160 mm or more, which allows for a long period and ensures a large limit deformation. From the same viewpoint, the total thickness of all the soft material layers 5 is more preferably 200 mm or more, and even more preferably 250 mm or more. [Example]
[0035] FEM analysis was carried out on Comparative Examples 1 to 10 (including Comparative Example 4-2) and Examples 1 to 10 (including Example 4-2) of the seismic isolation device of the present invention, and the results are described below. Analysis was performed for each comparative example and each example using a seismic isolation device model 1' as schematically shown in Figure 2. The seismic isolation device model 1' in each comparative example and each example comprises a pair of connecting steel plates 7' and a laminated structure 3' connected between the pair of connecting steel plates 7', and does not include a flange. The laminated structure 3' is formed by alternately stacking hard material layers 4' and soft material layers 5' along the axial direction, and does not include a coating layer. The connecting steel plates 7' have a square cross section perpendicular to the axis, and the four corners are angular. The laminated structure 3' has a square cross section perpendicular to the axis, and the four corners are curved by C-chamfering. The width of the laminated structure 3' is constant along the axial direction. Other specifications of each comparative example and each example are as shown in Tables 1 to 3 below. As shown in Tables 1 to 3, each comparative example does not satisfy the above formula (1), while each example satisfies the above formula (1). Comparative Example 4-2 and Example 4-2 differ from Comparative Example 4 and Example 4, respectively, only in the shear modulus of the soft material layer.
[0036] [Table 1]
[0037] [Table 2]
[0038] [Table 3]
[0039] For each of the comparative examples except for comparative example 4-2 and each of the examples except for example 4-2, horizontal deformation was generated by loading the seismic isolation device model 1' in the 0° direction and the 45° direction under a surface pressure of 20 MPa and 40 MPa until the shear strain reached 400% or until buckling occurred. For comparative example 4-2 and example 4-2, horizontal deformation was generated by loading in the 45° direction under a surface pressure of 40 MPa until the shear strain reached 400% or until buckling occurred. The shear stress-shear strain curves obtained in this manner for each of the comparative examples and examples are shown in Figures 3 to 8. The points where the shear stress-shear strain curves change from a positive gradient to a negative gradient indicate the timing at which buckling occurred. As shown in FIG. 2, the "0° direction" is a direction parallel to one side of the laminated structure 3', and the "45° direction" is a direction parallel to a diagonal line of the laminated structure 3'.
[0040] As can be seen from FIGS. 3 to 8, in Comparative Examples 1 to 10 (excluding Comparative Example 4-2), buckling occurred under a high surface pressure of 40 MPa, both in the horizontal deformation in the 0° direction and in the horizontal deformation in the 45° direction, just before the shear strain reached 400%. Furthermore, in Comparative Example 4-2, buckling occurred under a high surface pressure of 40 MPa, both in the horizontal deformation in the 45° direction, just before the shear strain reached 400%. On the other hand, in Examples 1 to 10 (excluding Example 4-2), buckling did not occur under a high surface pressure of 40 MPa, both in the horizontal deformation in the 0° direction and in the 45° direction, even up to a shear strain of 400%. Furthermore, in Example 4-2, buckling did not occur under a high surface pressure of 40 MPa, both in the horizontal deformation in the 45° direction, even up to a shear strain of 400%. Therefore, it can be seen that Examples 1 to 10 (including Example 4-2) can withstand high surface pressure more effectively than Comparative Examples 1 to 10 (including Comparative Example 4-2), and as a result, can withstand high surface pressure. [Industrial Applicability]
[0041] The seismic isolation device of the present invention is suitable for being placed between the superstructure and substructure of a structure (for example, buildings such as buildings, condominiums, detached houses, warehouses, and bridges) in order to suppress the transmission of earthquake vibrations to the structure. The seismic isolation device of the present invention is suitable for being provided on pillars so as to support the pillars of the structure, and for example, it is suitable for one or more devices to be provided on each pillar. [Explanation of symbols]
[0042] 1: seismic isolation device, 3: laminated structure, 4: hard material layer, 5: soft material layer, 6: covering layer, 7: connecting steel plate, 8: flange, f: fastening member, O: central axis, 1': seismic isolation device model, 3': laminated structure, 4': hard material layer, 5': soft material layer, 7': connecting steel plate, O': central axis
Claims
1. A seismic isolation device comprising a laminated structure having hard material layers and soft material layers alternately stacked in a vertical direction, A seismic isolation device that satisfies the following formula (1). [Equation 1] Here, in the above formula (1), [Equation 2] In the above formula (2), S １ : Ratio of the constrained area of the soft material layer to the free area per layer of the soft material layer S ２ : Ratio of the width of the soft material layer to the total thickness of all the soft material layers S ３ : 1000 times the ratio of the thickness of each hard material layer to the width of each soft material layer σ: Short-term allowable surface pressure (MPa) is.
2. The seismic isolation device according to claim 1 , wherein the soft material layer has a shear modulus of elasticity of 0.35 MPa or more.
3. 3. The seismic isolation device according to claim 1, wherein the total thickness of all the soft material layers is 160 mm or more.
Citation Information
Patent Citations
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Design method of base isolation building and special building constructed in the method
JP1996120973A
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JP2016028208A